During idling tests of a newly developed sport utility vehicle (SUV) under
tropical high-temperature conditions, the condenser surface temperature exceeded
the allowable range, degrading the air-conditioning system’s cooling
performance. In this study, a three-dimensional computational fluid dynamics
(CFD) model of the engine compartment flow field was established using
STAR-CCM+. The results reveal that under idling conditions, the kinetic energy
of hot air passing through the cooling module was insufficient to overcome the
pressure difference between the front and rear sections, thus inducing hot air
recirculation (HAR) and increasing the overall compartment temperature. To
address the unfavorable flow field characteristics, four structural improvements
were proposed and simulated for both flow and temperature fields. Through
comparative analysis, the optimal scheme was determined: installing a flow guide
baffle above the engine. Simulation results show that the airflow velocity above
and below the engine increased by 54% and 71%, respectively, and HAR was
effectively suppressed. The optimal scheme was further validated under
real-vehicle idle conditions, and the temperature deviation between simulation
and measurement was within 2%, confirming the reliability of the numerical
model. In addition, the optimized scheme was verified under three typical harsh
driving conditions, including hill climbing, high-speed climbing, and high-speed
driving. Both simulation and test results indicate that the scheme significantly
enhances airflow velocity in the engine compartment, with temperature errors
maintained within 5%. The present study effectively mitigates the compartment
temperature rise caused by HAR, and the proposed baffle scheme provides a
feasible solution for the thermal management design of new SUVs under both idle
and severe driving conditions.
